The Radio Frequency (RF) front end of an active antenna typically includes one or more arrays of radiating antenna elements. In a typical active antenna physical architecture, there is a one-to-one correspondence of radiating elements and transceivers, so a single transceiver would be coupled to a single radiating antenna element. Examples of active antennas include U.S. Patent Pub. No.: 2011/0032158, titled: PANEL ANTENNA HAVING SEALED RADIO ENCLOSURE, the disclosure of which is incorporated by reference.
An example of a conventional active antenna is illustrated in FIG. 1. In this example, an array of radiating elements is cross polarized. An array of ten +45 degree polarized radiating elements 12 and an array of ten −45 degree polarized radiating elements is illustrated. In this conventional structure, a transceiver is associated with each radiating element. The phase (degree of advance or delay for an RF signal) may be individually configured for each radiating element. In this example, there would be twenty transceivers 16 in typical active antenna architecture.
Such active antenna systems are often mounted at the top of towers. As it can be very expensive and/or dangerous to climb towers to repair or replace failed equipment, it may be desirable to provide an active antenna system that can withstand the loss of, for example, one of the transceivers that powers an individual antenna element or a sub-array.
Certain antenna beam characteristics may be controlled by adjusting the phase angles and power levels supplied to each antenna radiating element. For example, advancing a phase angle of radiating elements at the top of the array, while delaying phase angle at the bottom of the array, may steer the beam pattern downward. Adjusting relative power distribution (e.g., tapered at top and bottom) may also provide desired beam shaping and reduce side lobe formation. The transceivers are controlled to provide the desired phase and power relationships.
A disadvantage of known active antennas is that the one-to-one relationship between transceivers and radiating elements results in expensive antennas with high power consumption. An additional disadvantage is that a failure of a single transceiver may cause the array as a whole to operate out of compliance with specifications, even if the receiving transceivers and radiating elements are operating normally. Accordingly, an object of the present invention is to provide structure and methods of operation which reduce cost, provide more efficient operation, and restorable performance in the case of a loss of a transceiver.